T1573.002: Asymmetric Cryptography
Adversaries may employ a known asymmetric encryption algorithm to conceal command and control traffic rather than relying on any inherent protections provided by a communication protocol. Asymmetric cryptography, also known as public key cryptography, uses a keypair per party: one public that can be freely distributed, and one private. Due to how the keys are generated, the sender encrypts data with the receiver’s public key and the receiver decrypts the data with their private key. This ensures that only the intended recipient can read the encrypted data. Common public key encryption algorithms include RSA and ElGamal.
For efficiency, many protocols (including SSL/TLS) use symmetric cryptography once a connection is established, but use asymmetric cryptography to establish or transmit a key. As such, these protocols are classified as Asymmetric Cryptography.
Analyst context for executives and security teams
Asymmetric Cryptography (T1573.002) matters because encrypted command-and-control can make malicious traffic look like ordinary protected communications. The business issue is not that encryption is bad; it is that security teams may lose visibility into C2 if they rely only on protocol trust or perimeter signatures. This is especially relevant across Windows, Linux, macOS, ESXi, and network-device environments where encrypted outbound traffic may be normal and high volume.
Executive priority
Leaders should treat this as a visibility and resilience question: where does the organization have enough evidence to distinguish legitimate encrypted business traffic from potential C2? Priority decisions include whether SSL/TLS inspection is appropriate for selected risk areas, how its privacy and operational risks are governed, and whether network intrusion prevention and SOC processes can support incident decisions when payloads are encrypted. ATT&CK relationships show this behavior is used by multiple campaigns, groups, and malware families, including activity associated with finance, government, energy, aviation, transportation, MSP/ISP, and critical infrastructure contexts, so risk owners should validate coverage for high-value systems and network egress paths.
Technical view
For SOC, detection engineering, and IR teams, this is a command-and-control sub-technique under Encrypted Channel. MITRE does not provide specific detection text for this object, so validation should focus on local telemetry and the related DET0543 detection strategy where available. Confirm whether teams can observe encrypted outbound sessions, certificates, destinations, timing, volume, and endpoint/process context across the listed platforms: ESXi, Linux, macOS, network devices, and Windows. Because the parent technique notes that implementations may expose keys in malware samples or configuration files, IR workflows should preserve malware/configuration artifacts when available, without assuming payload inspection alone will be possible.
Likely telemetry
- Network connection metadata for encrypted sessions, including source, destination, ports, timing, duration, and volume
- SSL/TLS or other asymmetric-key handshake metadata where collected
- Certificate and public-key related metadata where lawful and technically available
- Proxy, firewall, and network intrusion prevention logs at network boundaries
- Endpoint process-to-network connection context on Windows, Linux, macOS, and ESXi where available
Detection direction
- Start by inventorying where encrypted egress is visible versus opaque; this technique often becomes material because defenders cannot inspect or correlate encrypted C2 paths.
- Validate DET0543-aligned analytics if available, but do not assume coverage because MITRE provides no official detection procedure in the supplied object.
- Tune for behavioral context rather than encryption alone: encryption is normal, so false positives should be reduced with asset role, destination reputation from approved sources, session patterns, and endpoint/process context.
- Review blind spots created by unmanaged endpoints, ESXi hosts, network devices, direct-to-Internet paths, and traffic that bypasses proxies or inspection points.
- Where SSL/TLS inspection is used, validate exception handling, certificate pinning impact, privacy constraints, and operational risk, consistent with the supplied references noting both decryption value and inspection risks.
Mitigation priorities
- Prioritize network visibility and egress control for high-value systems before broad payload decryption decisions.
- Use SSL/TLS inspection selectively where legally, operationally, and technically appropriate; govern exclusions and document risk acceptance.
- Use network intrusion prevention at network boundaries with signatures and policy controls, recognizing that encrypted content may limit payload-based inspection.
- Correlate network controls with endpoint and incident-response evidence so encrypted traffic can still be investigated through process, host, and artifact context.
- For compliance readiness, document where encrypted traffic is inspected, where it is not, and what compensating telemetry supports investigation and audit evidence.
Analyst notes and limits
This object is a sub-technique of Encrypted Channel and is mapped to command-and-control. The relationship set includes multiple campaigns, groups, and software families using the technique, which supports treating it as broadly relevant rather than niche. The supplied mitigations are SSL/TLS Inspection (M1020) and Network Intrusion Prevention (M1031). The supplied external references also highlight that decrypting SSL/TLS can help find hidden threats, while SSL inspection carries risks that must be managed.
MITRE did not provide official detection guidance in the supplied fields, and the related DET0543 content is named but not detailed here. This take does not establish active exploitation against any specific organization, guarantee detectability, or infer platforms beyond the supplied ATT&CK platform list. Local architecture, legal/privacy requirements, traffic patterns, and available telemetry are required to turn this into a concrete detection or control plan.
Asymmetric Cryptography
Adversaries may employ a known asymmetric encryption algorithm to conceal command and control traffic rather than relying on any inherent protections provided by a communication protocol. Asymmetric cryptography, also known as public key cryptography, uses a keypair per party: one public that can be freely distributed, and one private. Due to how the keys are generated, the sender encrypts data with the receiver’s public key and the receiver decrypts the data with their private key. This ensures that only the intended recipient can read the encrypted data. Common public key encryption algorithms include RSA and ElGamal.
For efficiency, many protocols (including SSL/TLS) use symmetric cryptography once a connection is established, but use asymmetric cryptography to establish or transmit a key. As such, these protocols are classified as Asymmetric Cryptography.
How security teams should use this page
Treat this object as behavior context, not an attribution claim. Validate the related groups, software, data sources, and mitigations against official ATT&CK relationships and your own telemetry before making control-coverage decisions.
Related techniques
This mirrors the MITRE pattern of making group, software, campaign, and technique relationships scannable. Relationship notes come from mirrored ATT&CK relationship text when available.
| Domain | ID | Name | Relationship / procedure |
|---|---|---|---|
| Enterprise | T1573 | Encrypted Channel | This object subtechnique of Encrypted Channel. |
Groups, software, and campaigns
G1018: TA2541
TA2541 is a cybercriminal group that has been targeting the aviation, aerospace, transportation, manufacturing, and defense industries since at least 2017. TA2541 campaigns are typically high volume and involve the use of commodity remote access tools obfuscated by crypters and themes related to aviation, transportation, and travel.[1][2]
G1047: Velvet Ant
Velvet Ant is a threat actor operating since at least 2021. Velvet Ant is associated with complex persistence mechanisms, the targeting of network devices and appliances during operations, and the use of zero day exploits.[1][2]
G0081: Tropic Trooper
Tropic Trooper is an unaffiliated threat group that has led targeted campaigns against targets in Taiwan, the Philippines, and Hong Kong. Tropic Trooper focuses on targeting government, healthcare, transportation, and high-tech industries and has been active since 2011.[1][2][3]
G1039: RedCurl
RedCurl is a threat actor active since 2018 notable for corporate espionage targeting a variety of locations, including Ukraine, Canada and the United Kingdom, and a variety of industries, including but not limited to travel agencies, insurance companies, and banks.[1] RedCurl is allegedly a Russian-speaking threat actor.[1][2] The group’s operations typically start with spearphishing emails to gain initial access, then the group executes discovery and collection commands and scripts to find corporate data. The group concludes operations by exfiltrating files to the C2 servers.
G1051: Medusa Group
Medusa Group has been active since at least 2021 and was initially operated as a closed ransomware group before evolving into a Ransomware-as-a-Service (RaaS) operation. Some reporting indicates that certain attacks may still be conducted directly by the ransomware’s core developers. Public sources have also referred to the group as “Spearwing” or “Medusa Actors.” [1] [2] Medusa Group employs living-off-the-land techniques, frequently leveraging publicly available tools and common remote management software to conduct operations. The group engages in double extortion tactics, exfiltrating data prior to encryption and threatening to publish stolen information if ransom demands are not met. [3] For initial access, Medusa Group has exploited publicly known vulnerabilities, conducted phishing campaigns, and used credentials or access purchased from Initial Access Brokers (IABs). The group is opportunistic and has targeted a wide range of sectors globally. [4]
G1042: RedEcho
G0049: OilRig
OilRig is a suspected Iranian threat group that has targeted Middle Eastern and international victims since at least 2014. The group has targeted a variety of sectors, including financial, government, energy, chemical, and telecommunications. It appears the group carries out supply chain attacks, leveraging the trust relationship between organizations to attack their primary targets. The group works on behalf of the Iranian government based on infrastructure details that contain references to Iran, use of Iranian infrastructure, and targeting that aligns with nation-state interests.[1][2][3][4][5][6][7]
G0080: Cobalt Group
Cobalt Group is a financially motivated threat group that has primarily targeted financial institutions since at least 2016. The group has conducted intrusions to steal money via targeting ATM systems, card processing, payment systems and SWIFT systems. Cobalt Group has mainly targeted banks in Eastern Europe, Central Asia, and Southeast Asia. One of the alleged leaders was arrested in Spain in early 2018, but the group still appears to be active. The group has been known to target organizations in order to use their access to then compromise additional victims.[1][2][3][4][5][6][7] Reporting indicates there may be links between Cobalt Group and both the malware Carbanak and the group Carbanak.[8]
G1044: APT42
APT42 is an Iranian-sponsored threat group that conducts cyber espionage and surveillance.[1] The group primarily focuses on targets in the Middle East region, but has targeted a variety of industries and countries since at least 2015.[1] APT42 starts cyber operations through spearphishing emails and/or the PINEFLOWER Android malware, then monitors and collects information from the compromised systems and devices.[1] Finally, APT42 exfiltrates data using native features and open-source tools.[2]
APT42 activities have been linked to Magic Hound by other commercial vendors. While there are behavior and software overlaps between Magic Hound and APT42, they appear to be distinct entities and are tracked as separate entities by their originating vendor.
S0615: SombRAT
S0022: Uroburos
Uroburos is a sophisticated cyber espionage tool written in C that has been used by units within Russia's Federal Security Service (FSB) associated with the Turla toolset to collect intelligence on sensitive targets worldwide. Uroburos has several variants and has undergone nearly constant upgrade since its initial development in 2003 to keep it viable after public disclosures. Uroburos is typically deployed to external-facing nodes on a targeted network and has the ability to leverage additional tools and TTPs to further exploit an internal network. Uroburos has interoperable implants for Windows, Linux, and macOS, employs a high level of stealth in communications and architecture, and can easily incorporate new or replacement components.[1][2]
S0687: Cyclops Blink
Cyclops Blink is a modular malware that has been used in widespread campaigns by Sandworm Team since at least 2019 to target Small/Home Office (SOHO) network devices, including WatchGuard and Asus. Cyclops Blink is assessed to be a replacement for VPNFilter, a similar platform targeting network devices.[1][2][3]
S1219: REPTILE
S1123: PITSTOP
PITSTOP is a backdoor that was deployed on compromised Ivanti Connect Secure VPNs during Cutting Edge to enable command execution and file read/write.[1]
S0455: Metamorfo
S0018: Sykipot
S0534: Bazar
Bazar is a downloader and backdoor that has been used since at least April 2020, with infections primarily against professional services, healthcare, manufacturing, IT, logistics and travel companies across the US and Europe. Bazar reportedly has ties to TrickBot campaigns and can be used to deploy additional malware, including ransomware, and to steal sensitive data.[1]
S0668: TinyTurla
S1141: LunarWeb
LunarWeb is a backdoor that has been used by Turla since at least 2020 including in a compromise of a European ministry of foreign affairs (MFA) together with LunarLoader and LunarMail. LunarWeb has only been observed deployed against servers and can use Steganography to obfuscate command and control.[1]
S0627: SodaMaster
SodaMaster is a fileless malware used by menuPass to download and execute payloads since at least 2020.[1]
S0126: ComRAT
C0014: Operation Wocao
Operation Wocao was a cyber espionage campaign that targeted organizations around the world, including in Brazil, China, France, Germany, Italy, Mexico, Portugal, Spain, the United Kingdom, and the United States. The suspected China-based actors compromised government organizations and managed service providers, as well as aviation, construction, energy, finance, health care, insurance, offshore engineering, software development, and transportation companies.[1]
Security researchers assessed the Operation Wocao actors used similar TTPs and tools as APT20, suggesting a possible overlap. Operation Wocao was named after an observed command line entry by one of the threat actors, possibly out of frustration from losing webshell access.[1]
C0039: Versa Director Zero Day Exploitation
Versa Director Zero Day Exploitation was conducted by Volt Typhoon from early June through August 2024 as zero-day exploitation of Versa Director servers controlling software-defined wide area network (SD-WAN) applications. Since tracked as CVE-2024-39717, exploitation focused on credential capture from compromised Versa Director servers at managed service providers (MSPs) and internet service providers (ISPs) to enable follow-on access to service provider clients. Versa Director Zero Day Exploitation was followed by the delivery of the VersaMem web shell for both credential theft and follow-on code execution.[1]
C0043: Indian Critical Infrastructure Intrusions
Indian Critical Infrastructure Intrusions is a sequence of intrusions from 2021 through early 2022 linked to People’s Republic of China (PRC) threat actors, particularly RedEcho and Threat Activity Group 38 (TAG38). The intrusions appear focused on IT system breach in Indian electric utility entities and logistics firms, as well as potentially managed service providers operating within India. Although focused on OT-operating entities, there is no evidence this campaign was able to progress beyond IT breach and information gathering to OT environment access.[1][2]
C0021: C0021
C0021 was a spearphishing campaign conducted in November 2018 that targeted public sector institutions, non-governmental organizations (NGOs), educational institutions, and private-sector corporations in the oil and gas, chemical, and hospitality industries. The majority of targets were located in the US, particularly in and around Washington D.C., with other targets located in Europe, Hong Kong, India, and Canada. C0021's technical artifacts, tactics, techniques, and procedures (TTPs), and targeting overlap with previous suspected APT29 activity.[1][2]
All related ATT&CK context
Mitigation direction
Object version and sync metadata
The fields below describe the current mirrored snapshot. When Glexia retains multiple ATT&CK source imports, you can open the table to compare the same object across releases (hashes and MITRE timestamps). For MITRE’s own release notes and roadmap, see ATT&CK resources — Updates .
Imported snapshots across ATT&CK releases (1)
| Release | Bundle imported | Object version | Modified | Status | Raw hash |
|---|---|---|---|---|---|
| 19.1 | 1.2 | Current bundle | daaa99678117… |
Mirrored ATT&CK source object
The raw object is retained through the mirrored ATT&CK source bundle and object hash. The raw endpoint returns the exact object from the mirrored bundle when available.
External references and citations
MITRE external references are preserved separately from Glexia analysis so citations remain traceable to their original source records.
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[1]
SANS Decrypting SSL
Butler, M. (2013, November). Finding Hidden Threats by Decrypting SSL. Retrieved April 5, 2016.
Open source URL -
[2]
SEI SSL Inspection Risks
Dormann, W. (2015, March 13). The Risks of SSL Inspection. Retrieved April 5, 2016.
Open source URL -
[3]
University of Birmingham C2
Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.
Open source URL -
[4]
mitre-attack T1573.002Open source URL
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